Bradley Perrett Beijing

It is probably no coincidence that modules for China's planned space station will be similar in size to powerful reconnaissance satellites. Rockets designed for one can launch the other. For the same reason, a new factory at Tianjin to build 6-8 outsize spacecraft a year has a clear military role.

The plant's best-known products will be modules for the space station that China plans to build around 2020, but another product line will be “large remote-sensing satellites.” The big spacecraft from Tianjin will join smaller payloads in a launch program that envisages sending up 30 rockets annually over the next seven years, more than doubling the rate of recent years.

Apart from assembly, the factory will be able to test its products, says the government of Tianjin, which is pushing hard to build itself up as one of China's top aerospace centers. Another facility in the city will build launcher rockets China is developing to replace and supplement its old hydrazine-fueled Long March series.

The city's economics and information committee says when the spacecraft plant is complete, it “will be able to build 6-8 outsize spacecraft a year, satisfying requirements for the space station, outsize [communications] satellites, large remote-sensing satellites, large unfolding precision structures and so on.”

The “large remote-sensing satellites” will presumably be military reconnaissance spacecraft. Representatives of the headquarters-level General Armaments Department, which along with the General Staff Department controls China's military satellites, attended the factory's foundation-laying ceremony in September, state media reported at the time. There was no mention of the air force, a sign that its ambitions to take over space operations continue to be rebuffed.

The new launcher family is related to the space station effort, since its largest member, the Long March 5, will be needed to loft modules. No hydrazine-fueled Long March has adequate throw weight, though the standard launcher for the manned space program, the Long March 2F, put the unmanned Tiangong 1 orbital laboratory into orbit in 2011.

Tiangong 1 had a launch mass of 8.5 tons and a diameter of 3.35 meters (11 ft.); the Tianjin plant is presumably needed for larger sizes. A planned cargo craft will also be 3.35 meters across and therefore could also be made at the current facilities of spacecraft builder CAST. But the space station will be built in three modules and have a mass of 60 tons, about 20 tons per module.